Name authorities:
https://www.loc.gov/cds/products/MDSConnect-name_authorities.html
https://www.loc.gov/item/2020445556/

Subjects:
https://www.loc.gov/item/2020445559/

Serials
https://doaj.org/docs/public-data-dump/

Other LOC materials

https://www.loc.gov/cds/

classifications:
https://www.loc.gov/item/2020445551/

https://www.loc.gov/aba/publications/FreeLCC/LCC_PL-PM2022OUT.pdf

I am looking at using constructed graphs as search parameters. I am noting some research papers here about graph search, which has a lot of noise about searching graphs and categorizing graphs.

https://dl.acm.org/doi/10.1145/1148170.1148254

https://arxiv.org/abs/1903.00553

https://www.sciencedirect.com/science/article/abs/pii/S095741742030539X

https://www.kdd.org/kdd2018/accepted-papers/view/graph-classification-using-structural-attention

Also interesting; https://arxiv.org/pdf/2210.12391.pdf